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Plan for giving buoyancy to chain cables
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Giving Buoyancy to Chain Cables.
obtained, which gives the highest perfection to this art~ and such a s it never could have reached by the old method. " An establishment of so much importance was worthy the patrori age of the goverhment, and it has accordingly honoured it with i t s special protection. The directm', who is a member of diff;~rent roya.l societies of arts and sciences, obtained at the exhibition of Ghent i n Flanders, in 18~20, the sine/" medal. At the last exhibition at I l a a , ' lem, in 18~5, he also received the silver medal; besides various medal for several inventions and improvements in the manufacturing o f " cards for wool and cotton. The royal society of Haarlem for domesti economy, assigned to the director of this fine establishment of nation. al industry, its medal of honour; and at the exhibitions both of G h e ~ t: and Haarlem, the king purchased many of the prlncipal specimen ~; produced by the manufactory."
l~lan for giving buoyancy to Chain Cables. :By John Poled Cort~tmander tl. ~Z S. 2]taidstone. Tri¢ advantage of a hemp cable over a chain one consists in i t s yielding more readily. XYhenever a chain cable forms a curve it r e quires a great power to draw that curve to a straight line. In m o d e rate depth ofwater~ the curve fot'med by the chain is very c o n s i d e r a ble; but in very shoal watt,', as Table Bay, where ships anchor i z l four fathoms, and lay nearly with 100 t'athoms cable out, the c a b l e is then nearly horizontal, and supported in a straight line by t h e ground; consequently when the ship receives a blow from the sea i ~ can yield little or nothing, and it snaps. Now~ I propose that in v e r y shoal water, as the cable cannot form a natural curve, to make an a r - tificial one, and I think in a very simple and efficient manner. E v e r y ship has, ,ahvavs, a few empty water casks at hand', four or ~ve ~,,*ood sized casks, would be quite enough, and any thing of a buoyant n a ture might be employed in aid of them. These casks should be k e p ~ slung with a hook and thimble in the lower part of the slings, a n d when coming to an anchor in moderate weather, I should veer out aL moderate quantity of cable, and when it comes on to blow fresh, a ~ I veered I would hook on a cask at every ten or fifteen fathoms, a c cording to the size of the cask and weight of the cable. These c a s k s , from their buoyancy, would festoon the cable when it became slack:~, anti when the shil) was forced, astern a~ain~ bvj a blow from the s e a , she would have to pull each of these casks down, and also astern, a_~ every cask wouhl be I:arther from the anchor with a straight cabl e~ than when festooned. In Table ]lay there is an under tow s e t t i r ~ out, and there is tbe same, I believe, in all bays when the wind blow¢~ strong into them ; which under tow would also make a resistance t o the casks, as the vessel drew taut her cable, and the ship would t h e r l be regularly eased to her anchor, and no sudden shock could be f e l t . I think a t"abie might be computed to show how much buoyancy i t would require Ibr a certain length of cable in a certain depth of w a r -
Report of Proceedings of the British ,~ssociation.
129
ter to give the most desirable curve ; and in fact I think you may give any elasticity :you like to a chain cable by this simple method. These casks~ it must be recollected, will be below the influence of the sea, and cannot be injured by it, and the only strain they will feel, will arise t?om their own buoyancy-. After the gale was over, you would, of course, heave in to your usual lengthof cabl% and take the casks ofL Merchant ships find tbe advantage of chain cables in so many ways, and there are so few objections to them beyond their liability to snap in shoal, and also in very deep water, that if any simple method couhl be devised to do away with these objections, there can be no question of its great utility. Whether festooning the cable, as I propose, in very shoal water, and in very deep water giving the cable a certain degree of buoyancy to relieve the sifip, will have that de. sired efihct, [ will leave others to judge.
~Mech. Mag. ¶ First Report of the Proceedings of the British .qssoeiationfor the 3dvancement of Science, assembled at York. [Continued from p. 9.] The same views are, perhaps, still more happily presented in the following paragraphs, which we really hope will go far to do away with the erroneous impression, still existing in some quartersi of an intentional interference on the part of the new institution with other scientific bodies. " B u t there is a defect in these separate societies, in respect to their own immediate objects, which I am sure no member of them would wish to dissemble, and which arises from the narrow basis or, which they are of necessity built. I t is nut only, that the constant converse of men, who, to borrow tile expression of Goldsmith, have often travelled over each other's minds, is not half so eit~ctua[ in striking out great and unexpected lights, as the occasional intercourse of those who have studied nature at a distance from each other, under various circumstances, and in different views; but it is also, gentlemen, that none o[" out' cxisting societies is able to concentrate the scattered forces even of its own science; they do not know, much less can they connect or employ, that extensive and growing body of humble labourers who are ready whenever they shall be called upon, to render their assistance." " What numberless suggestions, what a crowd of valuable but abortive hints are continually floating in the thoughts of philosophers, for the pursuit of which time is wanting to themselves[ :Now I say, gentlemen, that we have among us, scattered through the country, menwflh • n o~ t o a d op t t heseun executed hints, as they arise out of the profound and varied meditations of more experienced minds, men not incapable of surveying with accuracy a limited district, though they may not pretend to draw the general outline of the map~ or fill up the whole of its details. Many such there are who only wait for VoL. X . - - N o . ~.--AuGuST, 1832. 17
Giving Buoyancy to Chain Cables.
obtained, which gives the highest perfection to this art~ and such a s it never could have reached by the old method. " An establishment of so much importance was worthy the patrori age of the goverhment, and it has accordingly honoured it with i t s special protection. The directm', who is a member of diff;~rent roya.l societies of arts and sciences, obtained at the exhibition of Ghent i n Flanders, in 18~20, the sine/" medal. At the last exhibition at I l a a , ' lem, in 18~5, he also received the silver medal; besides various medal for several inventions and improvements in the manufacturing o f " cards for wool and cotton. The royal society of Haarlem for domesti economy, assigned to the director of this fine establishment of nation. al industry, its medal of honour; and at the exhibitions both of G h e ~ t: and Haarlem, the king purchased many of the prlncipal specimen ~; produced by the manufactory."
l~lan for giving buoyancy to Chain Cables. :By John Poled Cort~tmander tl. ~Z S. 2]taidstone. Tri¢ advantage of a hemp cable over a chain one consists in i t s yielding more readily. XYhenever a chain cable forms a curve it r e quires a great power to draw that curve to a straight line. In m o d e rate depth ofwater~ the curve fot'med by the chain is very c o n s i d e r a ble; but in very shoal watt,', as Table Bay, where ships anchor i z l four fathoms, and lay nearly with 100 t'athoms cable out, the c a b l e is then nearly horizontal, and supported in a straight line by t h e ground; consequently when the ship receives a blow from the sea i ~ can yield little or nothing, and it snaps. Now~ I propose that in v e r y shoal water, as the cable cannot form a natural curve, to make an a r - tificial one, and I think in a very simple and efficient manner. E v e r y ship has, ,ahvavs, a few empty water casks at hand', four or ~ve ~,,*ood sized casks, would be quite enough, and any thing of a buoyant n a ture might be employed in aid of them. These casks should be k e p ~ slung with a hook and thimble in the lower part of the slings, a n d when coming to an anchor in moderate weather, I should veer out aL moderate quantity of cable, and when it comes on to blow fresh, a ~ I veered I would hook on a cask at every ten or fifteen fathoms, a c cording to the size of the cask and weight of the cable. These c a s k s , from their buoyancy, would festoon the cable when it became slack:~, anti when the shil) was forced, astern a~ain~ bvj a blow from the s e a , she would have to pull each of these casks down, and also astern, a_~ every cask wouhl be I:arther from the anchor with a straight cabl e~ than when festooned. In Table ]lay there is an under tow s e t t i r ~ out, and there is tbe same, I believe, in all bays when the wind blow¢~ strong into them ; which under tow would also make a resistance t o the casks, as the vessel drew taut her cable, and the ship would t h e r l be regularly eased to her anchor, and no sudden shock could be f e l t . I think a t"abie might be computed to show how much buoyancy i t would require Ibr a certain length of cable in a certain depth of w a r -
Report of Proceedings of the British ,~ssociation.
129
ter to give the most desirable curve ; and in fact I think you may give any elasticity :you like to a chain cable by this simple method. These casks~ it must be recollected, will be below the influence of the sea, and cannot be injured by it, and the only strain they will feel, will arise t?om their own buoyancy-. After the gale was over, you would, of course, heave in to your usual lengthof cabl% and take the casks ofL Merchant ships find tbe advantage of chain cables in so many ways, and there are so few objections to them beyond their liability to snap in shoal, and also in very deep water, that if any simple method couhl be devised to do away with these objections, there can be no question of its great utility. Whether festooning the cable, as I propose, in very shoal water, and in very deep water giving the cable a certain degree of buoyancy to relieve the sifip, will have that de. sired efihct, [ will leave others to judge.
~Mech. Mag. ¶ First Report of the Proceedings of the British .qssoeiationfor the 3dvancement of Science, assembled at York. [Continued from p. 9.] The same views are, perhaps, still more happily presented in the following paragraphs, which we really hope will go far to do away with the erroneous impression, still existing in some quartersi of an intentional interference on the part of the new institution with other scientific bodies. " B u t there is a defect in these separate societies, in respect to their own immediate objects, which I am sure no member of them would wish to dissemble, and which arises from the narrow basis or, which they are of necessity built. I t is nut only, that the constant converse of men, who, to borrow tile expression of Goldsmith, have often travelled over each other's minds, is not half so eit~ctua[ in striking out great and unexpected lights, as the occasional intercourse of those who have studied nature at a distance from each other, under various circumstances, and in different views; but it is also, gentlemen, that none o[" out' cxisting societies is able to concentrate the scattered forces even of its own science; they do not know, much less can they connect or employ, that extensive and growing body of humble labourers who are ready whenever they shall be called upon, to render their assistance." " What numberless suggestions, what a crowd of valuable but abortive hints are continually floating in the thoughts of philosophers, for the pursuit of which time is wanting to themselves[ :Now I say, gentlemen, that we have among us, scattered through the country, menwflh • n o~ t o a d op t t heseun executed hints, as they arise out of the profound and varied meditations of more experienced minds, men not incapable of surveying with accuracy a limited district, though they may not pretend to draw the general outline of the map~ or fill up the whole of its details. Many such there are who only wait for VoL. X . - - N o . ~.--AuGuST, 1832. 17